+++ /dev/null
-*> \brief \b DTRMV
-*
-* =========== DOCUMENTATION ===========
-*
-* Online html documentation available at
-* http://www.netlib.org/lapack/explore-html/
-*
-* Definition:
-* ===========
-*
-* SUBROUTINE DTRMV(UPLO,TRANS,DIAG,N,A,LDA,X,INCX)
-*
-* .. Scalar Arguments ..
-* INTEGER INCX,LDA,N
-* CHARACTER DIAG,TRANS,UPLO
-* ..
-* .. Array Arguments ..
-* DOUBLE PRECISION A(LDA,*),X(*)
-* ..
-*
-*
-*> \par Purpose:
-* =============
-*>
-*> \verbatim
-*>
-*> DTRMV performs one of the matrix-vector operations
-*>
-*> x := A*x, or x := A**T*x,
-*>
-*> where x is an n element vector and A is an n by n unit, or non-unit,
-*> upper or lower triangular matrix.
-*> \endverbatim
-*
-* Arguments:
-* ==========
-*
-*> \param[in] UPLO
-*> \verbatim
-*> UPLO is CHARACTER*1
-*> On entry, UPLO specifies whether the matrix is an upper or
-*> lower triangular matrix as follows:
-*>
-*> UPLO = 'U' or 'u' A is an upper triangular matrix.
-*>
-*> UPLO = 'L' or 'l' A is a lower triangular matrix.
-*> \endverbatim
-*>
-*> \param[in] TRANS
-*> \verbatim
-*> TRANS is CHARACTER*1
-*> On entry, TRANS specifies the operation to be performed as
-*> follows:
-*>
-*> TRANS = 'N' or 'n' x := A*x.
-*>
-*> TRANS = 'T' or 't' x := A**T*x.
-*>
-*> TRANS = 'C' or 'c' x := A**T*x.
-*> \endverbatim
-*>
-*> \param[in] DIAG
-*> \verbatim
-*> DIAG is CHARACTER*1
-*> On entry, DIAG specifies whether or not A is unit
-*> triangular as follows:
-*>
-*> DIAG = 'U' or 'u' A is assumed to be unit triangular.
-*>
-*> DIAG = 'N' or 'n' A is not assumed to be unit
-*> triangular.
-*> \endverbatim
-*>
-*> \param[in] N
-*> \verbatim
-*> N is INTEGER
-*> On entry, N specifies the order of the matrix A.
-*> N must be at least zero.
-*> \endverbatim
-*>
-*> \param[in] A
-*> \verbatim
-*> A is DOUBLE PRECISION array of DIMENSION ( LDA, n ).
-*> Before entry with UPLO = 'U' or 'u', the leading n by n
-*> upper triangular part of the array A must contain the upper
-*> triangular matrix and the strictly lower triangular part of
-*> A is not referenced.
-*> Before entry with UPLO = 'L' or 'l', the leading n by n
-*> lower triangular part of the array A must contain the lower
-*> triangular matrix and the strictly upper triangular part of
-*> A is not referenced.
-*> Note that when DIAG = 'U' or 'u', the diagonal elements of
-*> A are not referenced either, but are assumed to be unity.
-*> \endverbatim
-*>
-*> \param[in] LDA
-*> \verbatim
-*> LDA is INTEGER
-*> On entry, LDA specifies the first dimension of A as declared
-*> in the calling (sub) program. LDA must be at least
-*> max( 1, n ).
-*> \endverbatim
-*>
-*> \param[in,out] X
-*> \verbatim
-*> X is DOUBLE PRECISION array of dimension at least
-*> ( 1 + ( n - 1 )*abs( INCX ) ).
-*> Before entry, the incremented array X must contain the n
-*> element vector x. On exit, X is overwritten with the
-*> tranformed vector x.
-*> \endverbatim
-*>
-*> \param[in] INCX
-*> \verbatim
-*> INCX is INTEGER
-*> On entry, INCX specifies the increment for the elements of
-*> X. INCX must not be zero.
-*> \endverbatim
-*
-* Authors:
-* ========
-*
-*> \author Univ. of Tennessee
-*> \author Univ. of California Berkeley
-*> \author Univ. of Colorado Denver
-*> \author NAG Ltd.
-*
-*> \date November 2011
-*
-*> \ingroup double_blas_level2
-*
-*> \par Further Details:
-* =====================
-*>
-*> \verbatim
-*>
-*> Level 2 Blas routine.
-*> The vector and matrix arguments are not referenced when N = 0, or M = 0
-*>
-*> -- Written on 22-October-1986.
-*> Jack Dongarra, Argonne National Lab.
-*> Jeremy Du Croz, Nag Central Office.
-*> Sven Hammarling, Nag Central Office.
-*> Richard Hanson, Sandia National Labs.
-*> \endverbatim
-*>
-* =====================================================================
- SUBROUTINE DTRMV(UPLO,TRANS,DIAG,N,A,LDA,X,INCX)
-*
-* -- Reference BLAS level2 routine (version 3.4.0) --
-* -- Reference BLAS is a software package provided by Univ. of Tennessee, --
-* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
-* November 2011
-*
-* .. Scalar Arguments ..
- INTEGER INCX,LDA,N
- CHARACTER DIAG,TRANS,UPLO
-* ..
-* .. Array Arguments ..
- DOUBLE PRECISION A(LDA,*),X(*)
-* ..
-*
-* =====================================================================
-*
-* .. Parameters ..
- DOUBLE PRECISION ZERO
- PARAMETER (ZERO=0.0D+0)
-* ..
-* .. Local Scalars ..
- DOUBLE PRECISION TEMP
- INTEGER I,INFO,IX,J,JX,KX
- LOGICAL NOUNIT
-* ..
-* .. External Functions ..
- LOGICAL LSAME
- EXTERNAL LSAME
-* ..
-* .. External Subroutines ..
- EXTERNAL XERBLA
-* ..
-* .. Intrinsic Functions ..
- INTRINSIC MAX
-* ..
-*
-* Test the input parameters.
-*
- INFO = 0
- IF (.NOT.LSAME(UPLO,'U') .AND. .NOT.LSAME(UPLO,'L')) THEN
- INFO = 1
- ELSE IF (.NOT.LSAME(TRANS,'N') .AND. .NOT.LSAME(TRANS,'T') .AND.
- + .NOT.LSAME(TRANS,'C')) THEN
- INFO = 2
- ELSE IF (.NOT.LSAME(DIAG,'U') .AND. .NOT.LSAME(DIAG,'N')) THEN
- INFO = 3
- ELSE IF (N.LT.0) THEN
- INFO = 4
- ELSE IF (LDA.LT.MAX(1,N)) THEN
- INFO = 6
- ELSE IF (INCX.EQ.0) THEN
- INFO = 8
- END IF
- IF (INFO.NE.0) THEN
- CALL XERBLA('DTRMV ',INFO)
- RETURN
- END IF
-*
-* Quick return if possible.
-*
- IF (N.EQ.0) RETURN
-*
- NOUNIT = LSAME(DIAG,'N')
-*
-* Set up the start point in X if the increment is not unity. This
-* will be ( N - 1 )*INCX too small for descending loops.
-*
- IF (INCX.LE.0) THEN
- KX = 1 - (N-1)*INCX
- ELSE IF (INCX.NE.1) THEN
- KX = 1
- END IF
-*
-* Start the operations. In this version the elements of A are
-* accessed sequentially with one pass through A.
-*
- IF (LSAME(TRANS,'N')) THEN
-*
-* Form x := A*x.
-*
- IF (LSAME(UPLO,'U')) THEN
- IF (INCX.EQ.1) THEN
- DO 20 J = 1,N
- IF (X(J).NE.ZERO) THEN
- TEMP = X(J)
- DO 10 I = 1,J - 1
- X(I) = X(I) + TEMP*A(I,J)
- 10 CONTINUE
- IF (NOUNIT) X(J) = X(J)*A(J,J)
- END IF
- 20 CONTINUE
- ELSE
- JX = KX
- DO 40 J = 1,N
- IF (X(JX).NE.ZERO) THEN
- TEMP = X(JX)
- IX = KX
- DO 30 I = 1,J - 1
- X(IX) = X(IX) + TEMP*A(I,J)
- IX = IX + INCX
- 30 CONTINUE
- IF (NOUNIT) X(JX) = X(JX)*A(J,J)
- END IF
- JX = JX + INCX
- 40 CONTINUE
- END IF
- ELSE
- IF (INCX.EQ.1) THEN
- DO 60 J = N,1,-1
- IF (X(J).NE.ZERO) THEN
- TEMP = X(J)
- DO 50 I = N,J + 1,-1
- X(I) = X(I) + TEMP*A(I,J)
- 50 CONTINUE
- IF (NOUNIT) X(J) = X(J)*A(J,J)
- END IF
- 60 CONTINUE
- ELSE
- KX = KX + (N-1)*INCX
- JX = KX
- DO 80 J = N,1,-1
- IF (X(JX).NE.ZERO) THEN
- TEMP = X(JX)
- IX = KX
- DO 70 I = N,J + 1,-1
- X(IX) = X(IX) + TEMP*A(I,J)
- IX = IX - INCX
- 70 CONTINUE
- IF (NOUNIT) X(JX) = X(JX)*A(J,J)
- END IF
- JX = JX - INCX
- 80 CONTINUE
- END IF
- END IF
- ELSE
-*
-* Form x := A**T*x.
-*
- IF (LSAME(UPLO,'U')) THEN
- IF (INCX.EQ.1) THEN
- DO 100 J = N,1,-1
- TEMP = X(J)
- IF (NOUNIT) TEMP = TEMP*A(J,J)
- DO 90 I = J - 1,1,-1
- TEMP = TEMP + A(I,J)*X(I)
- 90 CONTINUE
- X(J) = TEMP
- 100 CONTINUE
- ELSE
- JX = KX + (N-1)*INCX
- DO 120 J = N,1,-1
- TEMP = X(JX)
- IX = JX
- IF (NOUNIT) TEMP = TEMP*A(J,J)
- DO 110 I = J - 1,1,-1
- IX = IX - INCX
- TEMP = TEMP + A(I,J)*X(IX)
- 110 CONTINUE
- X(JX) = TEMP
- JX = JX - INCX
- 120 CONTINUE
- END IF
- ELSE
- IF (INCX.EQ.1) THEN
- DO 140 J = 1,N
- TEMP = X(J)
- IF (NOUNIT) TEMP = TEMP*A(J,J)
- DO 130 I = J + 1,N
- TEMP = TEMP + A(I,J)*X(I)
- 130 CONTINUE
- X(J) = TEMP
- 140 CONTINUE
- ELSE
- JX = KX
- DO 160 J = 1,N
- TEMP = X(JX)
- IX = JX
- IF (NOUNIT) TEMP = TEMP*A(J,J)
- DO 150 I = J + 1,N
- IX = IX + INCX
- TEMP = TEMP + A(I,J)*X(IX)
- 150 CONTINUE
- X(JX) = TEMP
- JX = JX + INCX
- 160 CONTINUE
- END IF
- END IF
- END IF
-*
- RETURN
-*
-* End of DTRMV .
-*
- END
OSDN Git Service
